• 300 patients enrolled in the study, including patients with and without the cognitive biomarker 
• On track to report topline data in October 2024 
• Alto to host investor day focused on ALTO-100 on September 9, 2024 

MOUNTAIN VIEW, Calif. / Jul 16, 2024 / Business Wire / Alto Neuroscience, Inc. (“Alto”) (NYSE: ANRO), a clinical-stage biopharmaceutical company focused on the development of novel precision medicines for neuropsychiatric disorders, today announced the completion of enrollment in its Phase 2b study of ALTO-100 in adults with major depressive disorder (MDD). Topline results from this study are expected to be reported in October 2024.

“The completion of enrollment in this study marks an important achievement,” said Amit Etkin, M.D., Ph.D., founder and chief executive officer of Alto Neuroscience. “We look forward to reporting topline results later this year, which, if positive, will propel us into Phase 3 and ultimately bring us one step closer to realizing the potential of precision psychiatry.”

The Phase 2b study is a randomized, double-blind, placebo-controlled study evaluating ALTO-100 in adults with major depressive disorder (MDD). The study is designed to determine the efficacy of ALTO-100 in MDD patients defined by an objective cognitive biomarker assessed prior to randomization. The Phase 2b study is enriched for patients exhibiting the predictive cognitive marker but also includes patients without the marker. The primary endpoint is the change from baseline to the end of the 6-week double-blind treatment period on the Montgomery-Åsberg Depression Rating Scale (MADRS), which is the standard regulatory endpoint in depression, in the prospectively identified patient population based on a specific memory deficit. The study was conducted across 34 sites in the U.S. and enrolled 300 adults with MDD. For more information about the ongoing study, visit ClinicalTrials.gov (NCT05712187).

“Major depressive disorder is among the most prevalent CNS conditions and is a leading cause of disability worldwide,” said Adam Savitz, M.D., Ph.D., chief medical officer of Alto. “If we are successful, new targeted therapies like ALTO-100 represent the future of psychiatric care. We are pleased with the receptivity to our neurocognitive test. The execution of this study demonstrates the potential for this test to be implemented broadly in clinical practice. We are grateful to the patients in the study, physicians, trial site staff, and partnerships with advocacy organizations for their efforts in helping us to reach this point.”

Alto Investor Day Focused on ALTO-100 in MDD

The company plans to host an investor day on September 9, 2024 focused on ALTO-100. The Company expects to provide information regarding the baseline characteristics of study participants, mechanistic and clinical rationale for ALTO-100, and the predictive cognitive test being used to select patients in the Phase 2b study. More details regarding the investor day are forthcoming and will be made available on the Company’s investor relations website.

About ALTO-100

ALTO-100 is a novel oral small molecule that has shown evidence of a pro-neurogenesis/neuroplasticity mechanism of action and first-in-class therapeutic potential. ALTO-100 is being developed for major depressive disorder (MDD). In a Phase 2a clinical trial, ALTO-100 demonstrated favorable safety and tolerability, and significantly greater treatment response in patients with an objectively defined cognitive biomarker.

About the ALTO-100 Cognitive Biomarker

Alto leverages its Precision Psychiatry Platform™ to identify brain-based biomarkers as predictors of response to medication. The predictive biomarker identified, and prospectively replicated, for ALTO-100 is a test of verbal memory, or the ability to recall lists of unrelated words. Verbal memory is a direct measure of hippocampal neuroplasticity; therefore, selecting patients based on poor performance on this test provides a clear biological link between the proposed pro-plasticity mechanism of ALTO-100 and this characteristic of responsive patients. The test used to compute the biomarker score is Alto’s digital adaptation of a well validated instrument that has been used in clinical practice for assessing memory for more than 80 years and is highly test-retest reliable. The web-based memory test is self-administered and can be completed by the patient in less than 20 minutes in any setting, including at home. This convenient, reliable, and efficient test enables high-quality data collection at a broad clinical scale.

About Alto Neuroscience

Alto Neuroscience is a clinical-stage biopharmaceutical company with a mission to redefine psychiatry by leveraging neurobiology to develop personalized and highly effective treatment options. Alto’s Precision Psychiatry Platform™ measures brain biomarkers by analyzing EEG activity, neurocognitive assessments, wearable data, and other factors to better identify which patients are more likely to respond to Alto product candidates. Alto’s clinical-stage pipeline includes novel drug candidates in depression, PTSD, schizophrenia, and other mental health conditions. For more information, visit www.altoneuroscience.com or follow Alto on X.

Forward Looking Statements

This press release may contain forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These statements may be identified by words such as “aims,” “anticipates,” “believes,” “could,” “estimates,” “expects,” “forecasts,” “goal,” “intends,” “may,” “plans,” “possible,” “potential,” “seeks,” “will” and variations of these words or similar expressions that are intended to identify forward-looking statements, although not all forward-looking statements contain these words. Forward-looking statements in this press release include, but are not limited to, statements regarding Alto’s expectations for the timing, progress, and results of the ALTO-100 study, and the final total number of subjects enrolled in the study. Actual results or events could differ materially from the plans, intentions and expectations disclosed in these forward-looking statements as a result of various factors, including uncertainties inherent in the timing, progress and completion of the ALTO-100 study and clinical development of ALTO-100; the availability and timing of results and other information from the ALTO-100 study; the success and impact of Alto’s approach to drug development; and other important factors, any of which could cause Alto’s actual results to differ from those contained in the forward-looking statements, which are described in greater detail in the section titled “Risk Factors” in Alto’s Quarterly Report on Form 10-Q for the fiscal quarter ended March 31, 2024 filed with the Securities and Exchange Commission (“SEC”) as well as in other filings Alto may make with the SEC in the future. Any forward-looking statements contained in this press release speak only as of the date hereof, and Alto expressly disclaims any obligation to update any forward-looking statements contained herein, whether because of any new information, future events, changed circumstances or otherwise, except as required by law.